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Whats that 'clunk' in my trans/diff ?

Discussion in 'VT - VX Holden Commodore (1997 - 2002)' started by Carlos the bastard, Jul 29, 2006.

  1. Carlos the bastard

    Carlos the bastard Carl

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    What can anyone tell me about a 'clunk' noise in the rear of my SS ?
    Its an auto and when coasting to a stop or going around corners at idle the noise appears.
    It was there when I bought the car 2 years ago, but was hardly noticable.
    I heard a rumour that this model had a noise where the trans and diff would take up slack under no load.
    It is definatly getting worse since I modified the engine from 220kw to 280kw.
    Am I killing my universals/drivetrain with the increase in power ?
    Its only got 115k on the clock.
    Advice would be appreciated.
    C
     
  2. OLS108

    OLS108 MR Helpful

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    More then Likley Diuff Chatter, or backlash Get ur Oil changed and the Additive added and see how it goes.
    Good luck
    Dave
     
  3. minux

    minux Infidel Bear

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    I would suggest the same, will take about 100km's of driving and it will magically dissapear.
     
  4. Carlos the bastard

    Carlos the bastard Carl

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    Sounds grate.I'll stuff some banana skins in with the sawdust and then sell it.
    Seriesly fellas is it that simple ?
    It had the oil + filter in the trans changed 5000k ago, but not the diff.
    I really like this car, had it 3 years and I recon its in its prime.
    Winding it out to 130 in second is like an aeroplane taking off pulling your head back.
    I have had to learn to drive with one hand as the other one is on my c***.
    My mississ calls it the 'dick pulla' and cant understand why it gets more back rubs (clean+polish) than her !
    I'll change the oil in the diff and see what happens.
    I respect other peers experiance.
    Here's hoping,
    C
     
  5. sixshooter

    sixshooter New Member

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    I got a similar problem with my super 6... I reckon its worn pinion bearings in the diff...as they wear the pinion shaft starts to slip forward and back clanking the pinion gear with the crownwheel in the diff...Mine is most noticable when putting the car into reverse.
     
  6. VZLAD

    VZLAD New Member

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    I had same problem in my diff.. Changed the oil with Motul.. GEARff Competition SAE75W140 oil and added the holden lsd additive at same time... No noises at all from diff now and the new oil seems to have given the diff a new lease of life... The Motul oil isnt cheap at $40 a litre ( needing 2 litres)and the Holden additive is $35 but damn it sure does the trick.. :thumbsup:
     
  7. brad_m_is

    brad_m_is New Member

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    hey ive got a vx supercharged and i wondered if that holden additive goes in the super6 diff aswell cause i got that slight diff clunk sometimes.
     
  8. sixshooter

    sixshooter New Member

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    May aswell use banana peals if the pinion bearings are the cause of the clanking !!!

    Actually the price of the additive might be cheaper than the bananas right now :D

    If the clank is like a hammer hitting metal it will be the pinion bearings !!!

    Does the diff whine ???

    My car had a slight whine and a slight audible clunk when going from reverse to drive and visa versa when I first got it... I thought it was the infamous supercharger whine at first but later found out it was the diff bearings... So I thought I'd put a new thicker synthetic oil in the diff to see if that helped quiet it down... 10,000 kms later = $40 wasted effort on oil and crawling under the car ... as it whines like a banshee now and the clanking is progrssively getting loader... it's rebuild time :bang:.

    It costs around $1200 for a fully rebuild open wheeler or swapping to a used LSD should end up costing around $600 for the LSD centre and $200 to get it checked out with new pinion bearings and seals fitted if you put the centre in and out of the car yourself.

    I'll be trying to find a good 2nd hand unit from a wreck and fit it myself first to see if it's any good and then look at the new seals and pinion bearings if it makes any noises.
     
  9. Carlos the bastard

    Carlos the bastard Carl

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    It's more of a clunk than a clank.
    I put some 80/140 expensive racing gear oil ($40 for 2L) and the GM additive ($38 for 100ml) in the diff last nite. Only done 60k so far so not shure if its fixed the noise.
    If this doesnt fix it then I will look at the driveshaft universals.
    Is there a problem with early VT's and a 2 piece setup?
    I read somewhere about changing to a one piece.
    It's definatly getting worse since modifing the mota.
    This is the price you pay for more power!
    Cheers for the advice.
    C
     
  10. dinodog

    dinodog New Member

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    try tightening the bolts that hold transmission to transmission x-member.
     
  11. minux

    minux Infidel Bear

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    Just remember, it could need an acid dip, it builds up coatings on the gears. I had to have mine acid washed, then have the additive added etc. Was fine after that.
     
  12. Don Sutton

    Don Sutton New Member

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    Sounds to me like the auto transmission line pressure is too high and the transmission changes back to first too soon causing a clunk in the diff.
    As the transmission ages this will become more prominent.
    If the transmission is controlled by a computer then a sensor is probably at fault telling the computer that the vehicle is going slower than it really is.
    Older vehicles of other brands particularly those using Borg Warner 35's used to have the line pressure controlled by the kickdown linkage to the throttle and were notorius for this problem.
     
  13. I own a 1988 VN Exec Sedan 3.8L Auto with about 300km on the clock. I have owned it for about 6 months now and am having similar problems as described above.

    My transmission makes a clunk often but not always when shifting into drive or reverse from neutral. The sound it makes is a deep "ding" and it sounds like it's coming from the rear axle / diff and it happens about 1 second after shifting. Kind of as if the drive shaft is taking up slack and then "ding" as it comes taught. The level of severity varies to almost as if it's not there to being really harsh.

    You can also faintly hear the sound if you manually shift down the gears into 2nd, 1st etc. I've noticed it now happens at slow speeds when gently slowing down and when the engine is pretty much idling you can hear the clunk as it downshifts a gear.

    I just recently changed all my springs and shocks (original panhard rod) so it's 30mm lower and i couldn't help but notice that more often now when shifting from neutral the clunk is less severe. Though the other day it happened really severely out of nowhere when slowing down as described before.

    Last time i was under my car i twisted the drive shaft to feel the play which was fairly little. When you gave it a good twist though you could hear a little ding from the auto.

    Apart from this the gears shift fine when driving, 1st to 2nd has quite a defined shift but then 2nd to 3rd and so on are seamless.
     
  14. WinterVX

    WinterVX Member

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    Yeah I have a bad case of the "clunk" in my car cause its manual...always engaging
    and disengaging the driveline when engaging the clutch.

    Im taking it to a trusted mechanic tomorrow night after work for him to have a quick
    look at the car and see what he thinks. Im hoping its just the universal joints
    as ive been told before that they are a bit loose and have play in them.... which
    they shouldnt have...just from wear and tear.....soon find out
     
  15. wilko

    wilko New Member

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    my wgn had a serious clunk like u describe Winter..felt like a tractor to drive , with a solid clunk when speeding up/slowing down/changing gear..also a slight whine in the lsd. Took it to WA diff centre yesterday and he showed me how worn the flexible rubber coupling at the front of the drive shaft was. Bought one and managed to fit it today..cost $350!!!.. but there was no sign of the clunk in the drivetrain on the test drive i just did :)..now as to the diff whine....lol will try that additive ur all talking about
     
  16. WinterVX

    WinterVX Member

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    Something so simple causing so much annoyance.......I just hope he can pin point
    it tomorrow night when I take it across for a check after work *fingers crossed*
     
  17. Hairy Eater

    Hairy Eater Banned

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    :) get out the old grease gun... pump in some good graphite grease .... even put in a few :) spoonfulls of graphite powder.... :)
     
  18. Trewman

    Trewman New Member

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    I had a new fault code come up the other day something along the lines of "Transmission Line Pressure error" or something like that. Now on gear changes I hear a loud clunk and there is more of a delay in gear changes. Also power isnt as much. Would this be a sensor? Ta :)
     
  19. cxcxcxvcvcvc

    cxcxcxvcvcvc Active Member

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    i to have the same prob i have been told that cars with irs are more likely to do this as it is a suspension problem however if its not a ping sound then theres a good chance its not the uni,s i think this is caused from the center yoke i have found that holding down the brake when puting the car into gear sometimes helps and yes my car does this when changing from drive to reverse i drive a 96 vs calais as well hope this helps
     
  20. IBLOWN

    IBLOWN Well-Known Member

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    Finally! This is right. The slop in the diff is taken up when the trans goes back to second and first gear. I wouldnt say anything is wrong with the trans, just the slop in the diff. Get under your car and have a little twist of the driveshaft when its in park. Then you'll understand what i mean.
     

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